Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, an electrode is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. The catheter should preferably be deflectable to permit proper positioning of the electrodes on its distal end within the heart.
Deflectable tip electrode catheters are well known. Such a catheter generally has a control handle at its proximal end for controlling deflection of the tip in one or more directions. For example, a particularly useful deflectable tip catheter is disclosed in U.S. Pat. No. Re. 34,502 to Webster, the disclosure of which is hereby incorporated by reference. This catheter comprises a puller wire that extends on-axis through an elongated reinforced catheter body and then off-axis in a deflectable tip portion. In this arrangement, longitudinal movement of the puller wire relative to the catheter body results in deflection of the catheter tip portion. Other examples of steerable catheters can be found in U.S. Pat. No. 5,431,168 to Webster entitled “Steerable Open-Lumen Catheter” and U.S. patent application Ser. No. 08/924,611 to Webster entitled “Omni-Directional Steerable Catheter,” the disclosures of which are hereby incorporated by reference.
One drawback to deflectable catheters is the kinking effect that can result when the distal end or tip section of the catheter is deflected. Frequently, the tip section of the catheter is made of a material considerably more flexible than the catheter body. As a result, the junction between the catheter body and the tip section tends to kink or bend when the tip section is deflected.